Search results
Results from the WOW.Com Content Network
The optic chiasm is found in all vertebrates, although in cyclostomes (lampreys and hagfishes), it is located within the brain. [2] [3] This article is about the optic chiasm of vertebrates, which is the best known nerve chiasm, but not every chiasm denotes a crossing of the body midline (e.g., in some invertebrates, see Chiasm (anatomy)).
The axons of the ipRGCs belonging to the retinohypothalamic tract project directly, monosynaptically, to the suprachiasmatic nuclei (SCN) via the optic nerve and the optic chiasm. [a] [2] The suprachiasmatic nuclei receive and interpret information on environmental light, dark and day length, important in the entrainment of the "body clock".
The suprachiasmatic nucleus or nuclei (SCN) is a small region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for regulating sleep cycles in animals. [ 1 ] [ 2 ] Reception of light inputs from photosensitive retinal ganglion cells allow it to coordinate the subordinate cellular clocks of the body ...
The optic chiasm of vertebrates involves the optic tract. The trochlear nerve is a motor nerve that innervates one of the muscles that move the contralateral eye ...
The optic tract is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and superior colliculus. [14] The optic tract represents the first stage in the visual pathway in which visual information is transferred in a homonymous nature. [15]
The optic tract grows from the retina to the optic tectum. Because dorsal and ventral are inverted in the anterior head region, the tracts grow at first toward the ventral side, to meet in the midline to form a chiasma. Since the optic tectum lies on the dorsal midbrain, each tract then continues dorsally to the contralateral optic tectum. [10]
Chiasm (anatomy), an X-shaped structure produced by the crossing over of the fibers, with the prefix chiasm- means cross examples include: A nerval chiasm, where either two nerves cross in the body midline (e.g. Optic chiasma) A crossing of fibres inside a nerve reversing their mapping; A tendinous chiasm, the spot where two tendons cross.
The origin of the contralateral organization, the optic chiasm and the major decussations on the nervous system of vertebrates has been a long standing puzzle to scientists. [2] The visual map theory of Ramón y Cajal has long been popular [3] [4] but has been criticized for its logical inconsistence. [5]